execlp() is a varargs function, so if NULL is defined as 0, the compiler
doesn't know that it needs to be converted to a null pointer constant;
add an explicit cast.
diff --git a/tcpdump.c b/tcpdump.c
index c915ae4..c7515b4 100644
--- a/tcpdump.c
+++ b/tcpdump.c
@@ -1340,7 +1340,7 @@
#else
setpriority(PRIO_PROCESS, 0, 19);
#endif
- if (execlp(zflag, zflag, filename, NULL) == -1)
+ if (execlp(zflag, zflag, filename, (char *)NULL) == -1)
fprintf(stderr,
"compress_savefile:execlp(%s, %s): %s\n",
zflag,
